Molecular marker and gene mapping

Molecular marker and gene mapping ppt
properties of molecular marker
types of molecular marker
mapping
genetic mapping
application of molecular marker

1. Molecular markers and gene mapping 1

2. Molecular marker Molecular marker is a fragment of DNA that is associated with a certain location within the genome. Molecular markers are used in molecular biology and biotechnology to identify a particular sequence of DNA in a pool of unknown DNA. They may be due to; Base pair changes Rearrangement Insertion or deletion Variation in the number of tandem repeats 2

3. A molecular marker must posses the following properties: It must be polymorphic so that diversity must be measured. It should be clearly distributed through out the genome. It should distinguishes the homologues and heterologous. 3

4. Types: RFLP(Restriction Fragment length polymorphism) AFLP(Amplified Fragment Length Polymorphism) RAPD( Randem Amplify of Polymorphic DNA) SNP(Short Nucleotide Polymorphism) VNTR(Variable Number Tandem Repeats) 4

5. Types: ```1).RAPD It doesn’t required sequence information and involved amplified random DNA fragments. It PCR based Dominant Used in genetic map and plant breeding 2).AFLP Restrictive enzyme cuts restrictive fragments of DNA under restriction process. F ast I nexpensive V ariable 5

6. VNTR A variable number tandem repeat is a location in a genome where a short nucleotide sequence is organized as a tandem repeat. These can be found on many chromosomes, and often show variations in length (number of repeats) among individual. Use  in genetic analysis VNTRs  have become essential to forensic crime investigations, via DNA fingerprinting 6

7. Applications of molecular markers: Measure of genetic diversity Finger printing Genotypic selection Identification of genotype Marker assisted selection Long shelf life of the DNA sample 7

8. Genetic Mapping: Genetic mapping is the processes of determining the order of and relative distance between genetic markers on a chromosome. It is based on recombination frequency. 8

9. Recombination Frequency: Recombination fraction is the measure of the distance between two loci. Two loci that show 1% recombination are defined as being 1 centimorgan (cM) apart in a genetic map. 1 map unit= 1cM Two genes that undergo independent assortment have recombination frequency of 50 percent and are located on non homologous chromosome or far apart on the same chromosome=Unlinked Genes with recombination frequency less than 50% are on the same chromosome= Linked 9

10. Calculation of Recombination Frequency: The percentage of recombination progeny produced in a across is called the recombination frequency. RecombinatioFrequency: =no of recombinant progeny ×100 total no of progeny 10

11. Purpose and uses: The purpose of genetic mapping is to determine the linear order and distance of separation among the genes that are linked to each other along the same chromosome. They are useful in predicting results of dihybrid and trihybrid crosses. A genetic map can provide plant and animal breeders with helpful information for improving agriculturally important strains through selective breeding. Useful from evolutionary point of view. A comparison of genetic maps for different species can improve our understanding of the evolutionary relationships among those species. 11

12. Limitations: Map generated by genetic techniques is rarely sufficient for directing the sequences phase of a genome project. This is for two reasons: The resolution of genetic map depends on the number of crossovers that have been scored. Genes that are several tens of kb apart may appear at the same position in the genetic Map. Genetic Maps have limited accuracy. 12